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Maven java: package does not exist

I am making a discord bot in java with JDA and I wanted to try to host it. I found out the best way to build an IntelliJ project is with maven. If I run mvn install i get the following error.
> java: package net.dv8tion.jda.api does not exist
I searched stack overflow and think I need to add a dependency but because this is my first time using java I really can't find out how to implement it in my project. Can anyone tell me how to fix the problem and how to implement it?
Here is my pom file.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<groupId>bananaaction</groupId>
<artifactId>DiscordBot</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>net.dv8tion</groupId>
<artifactId>JDA</artifactId>
<version>4.2.0_222</version>
</dependency>
</dependencies>
<repositories>
<repository>
<id>jcenter</id>
<name>jcenter-bintray</name>
<url>https://jcenter.bintray.com</url>
</repository>
</repositories>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId> <!-- In Red -->
<configuration>
<archive>
<manifest>
<mainClass>com.bananaaction.Main</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

As you guessed, the problem is that you didn't include JDA as a dependency (library).
In order to do this, add this to the pom.xml:
<dependencies>
<dependency>
<groupId>net.dv8tion</groupId>
<artifactId>JDA</artifactId>
<version>4.2.0_222</version>
</dependency>
</dependencies>
<repositories>
<repository>
<id>jcenter</id>
<name>jcenter-bintray</name>
<url>https://jcenter.bintray.com</url>
</repository>
</repositories>
See the README of JDA for details.
The first section (<dependencies>) declares your dependencies (libraries).
Here, you add a dependency with the group id net.dv8tion and artifact id JDA with version 4.2.0_222 (the latest version at the time of writing this (may 2nd, 2020).
The second section (<repositories>) defines where to look for. JDA is not in the maven central (the default) repository but in the jcenter repository so you need to add the jcenter repository to your pom.xml.
If you package it to a JAR, dependencies will not be included. In order to do this, you can use the maven-assembly-plugin, for example.
You can add the plugin to the pom.xml wth the following code in the <plugins> secion:
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>yourPackage.yourClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
Integrated in your pom.xml, it could look like this:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<groupId>com.bananaaction</groupId>
<artifactId>IdeaProjects</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>net.dv8tion</groupId>
<artifactId>JDA</artifactId>
<version>4.2.0_222</version>
</dependency>
</dependencies>
<repositories>
<repository>
<id>jcenter</id>
<name>jcenter-bintray</name>
<url>https://jcenter.bintray.com</url>
</repository>
</repositories>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>yourPackage.yourClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Don't forget to change the main class, however.

Maven assembly jar execution Could not find or load main class Caused by: java.lang.ClassNotFoundException

I have been trying, for several days now, to create an executable jar file for my muli-module maven project, sadly I have had no luck on doing it.
I know that there are a lot of similar questions already, but, even by following the answers, i cannot manage to run the jar I make.
I am using the maven-assembly plugin, so that my jar contains all the required dependencies, here is the pom:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>tam-authentication</artifactId>
<name>tam-authentication</name>
<description>authentication tam project</description>
<parent>
<groupId>com.netcomgroup.eu</groupId>
<artifactId>TAM</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<java.version>11</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
</plugin>
</plugins>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>"fully qualified class name"</mainClass>
</manifest>
</archive>
</configuration>
<executions>
<execution>
<id>make-assembly</id>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
<dependencies>
...
dependencies from other modules
...
</dependencies>
</project>
futhermore i have another probably related problem regarding jar creation with a common library included:
using Eclipse as IDE, whenever I run as > maven install on the multimodule project, I often get jars failing over correct imports, that I need to delete and import again to complete the java building process correctly. Sometimes i simply must run maven install several times in a row to make the jar building process succeed.
I don't know if the second problem is related but i guess there is some mistake I cannot see in the multi module project jar building.

First of all, as per your pom.xml you did not provide the fully qualified Main class name in your dependency. Second if you provided the Main class name, then after "mvn clean install", it would create 2 jars - one with artifact name and one with "jar-with-dependencies" and you have to user "jar-with-dependencies".
Also i don't think you need to use pluginManagement tag as an extra step. I have just modified a bit your pom below, please try this and check.
<?xml version="1.0" encoding="UTF-8"?>
4.0.0
<artifactId>tam-authentication</artifactId>
<name>tam-authentication</name>
<description>authentication tam project</description>
<parent>
<groupId>com.netcomgroup.eu</groupId>
<artifactId>TAM</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<properties>
<java.version>11</java.version>
</properties>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>{Your fully qualified Main class eg - abc.cde.Main}</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
...
dependencies from other modules
...
</dependencies>

Packing Source Code and Dependencies

I am trying to build a jar package using Maven with source code and all dependencies. The problem is that Maven is no packing the source code only the dependencies.
Do I need to set a configuration to pack the source code too?
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>courier-perf-test</groupId>
<artifactId>courier-perf-test</artifactId>
<version>0.0.1-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>ze.delivery.HTTPRequestClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.json/json -->
<!-- https://mvnrepository.com/artifact/com.googlecode.json-simple/json-simple -->
<dependency>
<groupId>com.googlecode.json-simple</groupId>
<artifactId>json-simple</artifactId>
<version>1.1.1</version>
</dependency>
</dependencies>
</project>

Use src as the descriptorRef in your assembly-plugin configuration to create source archives for your project or it might be better to use the predefined descriptor project:
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
<descriptorRef>src</descriptorRef>
</descriptorRefs>
OR:
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
<descriptorRef>project</descriptorRef>
</descriptorRefs>
Reference: maven-assembly-plugin

Error: Could not find or load main class. Running maven jar-with-dependencies

I am using Maven to manage a personal project and am getting this maven error whenever I try to run my jar with dependencies.
$ java -jar .\SpotifyAutomation-1.0-SNAPSHOT-jar-with-dependencies.jar
Error: Could not find or load main class SpotifyRunner
(I do a clean and install before running).
My pom file looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>SpotifyAutomation</groupId>
<artifactId>SpotifyAutomation</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib</classpathPrefix>
<mainClass>SpotifyRunner</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.seleniumhq.selenium</groupId>
<artifactId>selenium-server</artifactId>
<version>3.4.0</version>
</dependency>
<dependency>
<groupId>se.michaelthelin.spotify</groupId>
<artifactId>spotify-web-api-java</artifactId>
<version>1.5.0</version>
</dependency>
</dependencies>
Any insight on how I might go about fixing this? I have tried switching around my classpathPrefix but to no avail. My project has one module and one package.
My project structure is shown in the below image:
Project Structure

Build WAR only once during mvn clean package

I have a maven project that should build war file. When I run mvn clean package I see in log that at first it makes default-war:
--- maven-war-plugin:2.3:war (default-war) # my-artifact---
Packaging webapp
And after that it makes the war:
--- maven-war-plugin:2.3:war (war) # my-artifact---
Packaging webapp
My pom.xml looks like:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.my.group</groupId>
<version>1.0.0-SNAPSHOT</version>
<artifactId>my-artifact</artifactId>
<packaging>war</packaging>
<dependencies>
<...>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<archive>
<manifest>
<addDefaultImplementationEntries>true</addDefaultImplementationEntries>
<addClasspath>true</addClasspath>
</manifest>
<manifestEntries>
<Implementation-Build>${project.artifactId}-${project.version}</Implementation-Build>
<Build-Time>${timestamp}</Build-Time>
<Implementation-Revision>${myapp.revision}</Implementation-Revision>
<Implementation-CommittedRevision>${myapp.committedRevision}</Implementation-CommittedRevision>
<Implementation-CommittedDate>${myapp.committedDate}</Implementation-CommittedDate>
</manifestEntries>
</archive>
<webXml>src/main/webapp/WEB-INF/web.xml</webXml>
</configuration>
<executions>
<execution>
<id>war</id>
<phase>package</phase>
<goals>
<goal>war</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
So what I want is to disable building of default-war.

You should remove the <executions> tag from the maven-war-plugin configuration. By default, this plugin will execute at the package phase, without any configuration. This would be the correct configuration:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<archive>
<manifest>
<addDefaultImplementationEntries>true</addDefaultImplementationEntries>
<addClasspath>true</addClasspath>
</manifest>
<manifestEntries>
<Implementation-Build>${project.artifactId}-${project.version}</Implementation-Build>
<Build-Time>${timestamp}</Build-Time>
<Implementation-Revision>${myapp.revision}</Implementation-Revision>
<Implementation-CommittedRevision>${myapp.committedRevision}</Implementation-CommittedRevision>
<Implementation-CommittedDate>${myapp.committedDate}</Implementation-CommittedDate>
</manifestEntries>
</archive>
<webXml>src/main/webapp/WEB-INF/web.xml</webXml>
</configuration>
</plugin>